Annual seasonal influenza vaccine manufacturing cycles align with temperate country seasonality in each hemisphere, yet influenza seasonality is poorly defined for many countries. The study introduces a novel and universal approach to defining and classifying seasonality that can be used to classify any country's influenza vaccine cycle alignment.

Influenza vaccines are important for prevention of influenza-associated hospitalization. However, the effectiveness of influenza vaccines can vary by year and influenza type and subtype and mechanisms underlying this variation are incompletely understood. Assessments of serologic correlates of protection can support interpretation of influenza vaccine effectiveness in hospitalized populations.

A field effectiveness evaluation of the influenza vaccine among children younger than five years is important due to the high burden of influenza in this age group. The epidemiology of influenza virus changes rapidly each year. Moreover, the development of a new type of influenza vaccine is accelerating, necessitating a new field effectiveness evaluation.

The 2017/18 winter influenza season in Hong Kong SAR started in early January 2018, predominated by influenza B/Yamagata. We collaborated with private medical practitioners of our sentinel surveillance system to collect respiratory specimens and clinical information from patients with influenza-like illness for estimation of the influenza vaccine effectiveness (VE) using the test-negative case-control design. We found that the overall VE was 59.1% (95%CI 41.1 to 71.8%) against all influenza and 53.5% (95%CI...

Although pregnant women are believed to have elevated risks of severe influenza infection and are targeted for influenza vaccination, no study to date has examined influenza vaccine effectiveness (IVE) against laboratory-confirmed influenza-associated hospitalizations during pregnancy, primarily because this outcome poses many methodological challenges.

Understanding the complexity of influenza subtype seasonality is critical to promoting a suitable vaccination program. Our study aims to identify and compare the seasonality and epidemiological features of seasonal influenza subtypes after the 2009 A/H1N1 pandemic and to lay a foundation for further investigation into the social and environmental factors affecting seasonal influenza transmission.

Several studies have demonstrated the role of meteorological parameters in the seasonality of influenza viruses in tropical and subtropical regions, most importantly temperature, humidity and rainfall.

Influenza vaccine effectiveness (VE) varies by season, circulating influenza strain, age, and geographic location. There have been few studies of influenza VE among hospitalized children, particularly in Europe and the Middle East.

In the United States it is recommended that health care providers offer influenza vaccination by October, if possible. However, if the vaccine's effectiveness soon begins to wane, the optimal time for vaccination may be somewhat later. We examined whether the effectiveness of influenza vaccine wanes during the influenza season with increasing time since vaccination.

In the United States, annual vaccination against seasonal influenza is recommended for all persons aged ≥6 months (https://www.cdc.gov/flu/protect/whoshouldvax.htm). Effectiveness of seasonal influenza vaccine varies by season. During each influenza season since 2004-05, CDC has estimated the effectiveness of seasonal influenza vaccine to prevent laboratory-confirmed influenza associated with medically attended acute respiratory illness (ARI). This interim report uses data from 3,254 children and adults e...

As part of the U.S. Department of Health and Human Services (HHS) Pandemic Influenza Plan preparedness and response strategy, the National Pre-Pandemic Influenza Vaccine Stockpile (NPIVS) program was established by the Biomedical Advanced Research and Development Authority (BARDA) in 2005 with the goal of building and maintaining a stockpile of vaccines for influenza viruses with pandemic potential to vaccinate 20 million people in the critical workforce in the event of a pandemic. The NPIVS program continu...

Tradeoffs exist between efforts to increase influenza vaccine uptake, including early season vaccination, and potential decreased vaccine effectiveness if protection wanes during influenza season. U.S. older adults increasingly receive vaccination before October. Influenza illness peaks vary from December to April.

The current seasonal influenza vaccine confers only limited protection due to waning antibodies or the antigenic shift and drift of major influenza surface antigens. A universal influenza vaccine which induces broad cross-protection against divergent influenza viruses with a comparable or better efficacy to seasonal influenza vaccines against matched strains will negate the need for an annual update of vaccine strains and protect against possible influenza pandemics. Areas covered: In this review, we summar...

Influenza and pneumonia are leading causes of morbidity and mortality among the elderly. Although vaccination is a main strategy to prevent these infectious diseases, concerns remain with respect to vaccine effectiveness.

The effects of repeated influenza vaccination in children are not well understood. In this study, we evaluated previous vaccination effects on antibody response after vaccination with trivalent inactivated influenza vaccine (IIV) or quadrivalent live-attenuated influenza vaccine (LAIV) among school-aged children (5-17 years) across 3 seasons.

Seasonal influenza vaccination is the most effective way to prevent influenza virus infection and its complications. Currently, China has licensed trivalent (IIV3) and quadrivalent inactivated influenza vaccine (IIV4), including split-virus influenza vaccine and subunit vaccine. In most parts of China, influenza vaccine is a category Ⅱ vaccine, which means influenza vaccination is voluntary, and recipients need to pay for it. To strengthen the technical guidance for prevention and control of influenza and...

During May 20-October 13, 2018,* low levels of influenza activity were reported in the United States, with a mix of influenza A and B viruses circulating. Seasonal influenza activity in the Southern Hemisphere was low overall, with influenza A(H1N1)pdm09 predominating in many regions. Antigenic testing of available influenza A and B viruses indicated that no significant antigenic drift in circulating viruses had emerged. In late September, the components for the 2019 Southern Hemisphere influenza vaccine we...

The enhanced safety surveillance for seasonal influenza vaccines established by the European Medicines Agency is required each season. Therefore, a registry capable of rapidly detecting and evaluating potential new safety concerns is needed. The aim of the study is to demonstrate the effectiveness of the vaccine information system of the Valencia region to make a rapid assessment of the influenza vaccine safety and describe the safety of the two vaccine types used in the 2017/2018 season.

Influenza infection could be more effectively controlled if a multi-purpose vaccine with the ability to induce responses against most, or all, influenza A subtypes could be generated. Conserved viral proteins are a promising basis for the creation of a broadly protective vaccine. In the present study, the immunogenicity and protective properties of three recombinant proteins (vaccine candidates), comprising conserved viral proteins fused with bacterial flagellin, were compared.

Vaccine effectiveness (VE) against influenza B was derived separately for Victoria and Yamagata lineages across eight seasons (2010-11 to 2017-18) in Canada when trivalent influenza vaccine was predominantly used. VE was ≥50% regardless of lineage match to circulating viruses, except when the vaccine strain was unchanged from the prior season.

Seasonal influenza can lead to pneumonia. In Hong Kong, deaths from pneumonia increased steadily from 2001 to 2015, and pneumonia was the second most common cause of death between 2012 and 2015. The seasonal influenza vaccine and pneumococcal vaccine have been clinically proven as effective measures against these two diseases among older adults, who are at particularly high risk. Despite the availability of vaccine subsidies, however, more than 60% of older adults in Hong Kong remain unvaccinated against pn...

Due to competing health priorities, low- and middle-income countries (LMIC) may need to prioritize between different influenza vaccine risk groups. Risk group prioritization may differ in LMIC based upon programmatic feasibility, country-specific prevalence of risk conditions and influenza-associated morbidity and mortality.